808 trigger technique?

[Fraser, Colin J]

> -----Original Message-----
> From: john tuffen [mailto:john at clutter.globalnet.co.uk]
> Sent: 15 May 2000 09:48
> To: synth-diy; david leigh
> Subject: Re: 808 trigger technique?
> 
> [You might find that the 808 trigger inputs are -ve going 
> pulses - I know
> that the CR8000 is...]
> 
> But that's just a simple software mod ;-)

The 808 trigger pulses are positive going, 1ms pulses between roughly 4 and
14 volts.
The common accent line is switched thru a pair of transistors separate TTL
lines to create the pulses for each instrument.
You'll find the sounds trigger at very low levels unless you step up the
microcontroller outputs somehow.
The easiest way would be to copy the circuitry from the 808 and use one of
the trigger outputs on the PIC to switch the accent on and off.

I've been meaning to do an AVR based midi to trigger convertor with a DAC to
provide accent levels for a while, but haven't found the time yet...

Colin f